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| This paper compares the topology, operation principle and electromagnetic performance of 8/6-pole flux-switching permanent magnet (FSPM) machine and 8/6-pole doubly-salient permanent magnet (DSPM) machine, including air gap field distributions, flux-linkage, back EMF, cogging torque, winding inductance, static torque, and end-effect, etc. Firstly, the static characteristics in 4-phase mode are derived based on finite element analysis (FEA). Secondly, the 2-phase mode is operated under brushless dc and brushless ac conditions, respectively. The torque components and torque ripple are modeled analytically, on the basis of which the torque capability is compared. In addition, the influences of rotor-skewing on the waveforms of static characteristics are investigated. Finally, experiments on a prototype machine of the 8/6-pole DSPM motor are given to validate the theoretical analysis. It is found that the most significant difference between the two machines is in the flux-linkage waveform. In DSPM machine, phase flux-linkage is unipolar, which compromises back EMF per coil and torque capability. In FSPM machine, phase flux-linkage is bipolar, and hence it exhibits significantly higher torque density. This paper lays a foundation for the design and control of the brushless machines having magnets in the stator with doubly-salient topology. |
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| Keywords:Brushless machines, doubly-salient, finite element analysis, flux switching, permanent magnet |
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